Process for simultaneously dyeing and partially saponifying cellulose acetate staple fibers



Patented Nov. 4, 1 952 PROCESS FGR SiMULTANEOUSLY" DYEING AND PARTIALLY 'SAPONIFY-ING CELLU LOSE" ACETATE STAPLE FIBERS homas- .H- Hill ard, nrnmmondvine, Q e

Canada, assignor' to Canadian Celanese Limit-ed', Montreal, Quebec, Canada, a corporation of Canada No, Drawing." ennlicationiflctclierzl. 19%,

Serial No. 122,835

This? inv tion r la es to" a p ess fbrdyeing textile materials and relates more particularly to 'a' process fordyeing textile fibers.

This application is a continuation-impart of m application s. No. 81,997, filed March 17, 1949.

An important object of this inventionis the. provision of a novel process for dyeing textile fibers which will be'especially simple and effi'cient Y in operation.

A further "object of this invention is; the provision of a process for dyeing textile fibers'wherein the fibers are dyed as'they flow through a passageway in admixture with a-dyebath.

treatment with a dyebath have not been 0 mg pletely satisfactory in that they did not produce dyeing's of uniform shade. On contact: with the dyebath, the textile fibers/tend? dto mat,.o r hunch together forming channels through whichithe major portion of the dyebath "flowed. As a result only those textile fibers that were adjacent the channels came into intimate contact with fresh dyebath during the entire dyeing period and were accordingly dyeda deeper shade than the textile fibers that were removed or spaced from said channels.

I have: now discovered that textile fibers. may

be readily dyed a uniform shade by forming a free-flowing mixture thereof with a dyebath and causing the mixture to flow through a passageway as the dyeing takes place. By carrying out the dyeing in this manner, no matting or bunching of the textile fibers takes place. As a result, the dyebath'has free access to each of the textile fibers during the entire dyeing period andall of the textile fibers will be dyed in a uniform shade. The mixture of textile fibers and dyebath should have a fiber content of less than about 2% by weight, since, with a higher fiber content,- the mixture will not flow freely and the dyebath will not have access to all of the textile fibers and may dye them non-uniformly. l

The process of this invention may advantageously be carried'out in an apparatus of the type disclosed in my application S. No. 81,997, referred to above. As set forth in this application, the apparatus comprises an enclosed passageway through which flows the mixture of textile fibers "and dyebath; The passageway is preferably-provided at spaced points along its length with baffles to impart turbulence t0. the mixture flowing therethrough so as to insurea thorough mixing of the textile fibers and the dyebath. To insure a uniform treatment of the textile fibers, the discharge end of the passageway is. raised above its feed end so as to keep the passageway filled at all times. The apparatus may also include means for producing staple fibers from continuous filamerits and for directing the staplev fibers as they are formed into the enclosed passageway. It is, however, possible to employ staple fibers that have been formed on separate apparatus or to employ natural fibers of staple length. At the discharge end of the passageway, means may be provided to separate the dyed textile fibers from the dyebath, .to wash, the textile fibers free from excess dyebath, to drain the wash water from'the textile fibers. and, in addition, to dry the textile fibers.

The process of my invention is particularly suited for the dyeing of staple fibers having a basis of cellulose acetate or other organic acid ester of cellulose with a solvent dyebath using either vat, acid, indigosol or direct acetate dyes. It: may also be employed for both dyeing and-partially or completely saponifying staple fibers hav- .ing' a basis of cellulose acetate or other organic acid ester of cellulose. In this case, the dyebath may contain cotton dyes or other dyes having an afiinity for cellulosic. material, which will dye the staple fibers as the saponification thereof proceeds. The process of my invention may also be employed for dyeing other types of textile fibers in any desired color and shade by employing a dyebath of a composition suited to the nature of the textile fiber being dyed.

For the solvent dyeing of staple fibers having a basis of cellulose acetate or other organic acid ester of cellulose, the dyebath will contain, in addition to the dyestuff, an organic liquid solvent for the dyestuff, which organic liquid is not a solvent for the organic acid ester of cellulose but may be a swelling agent therefor. Suitable organic liquid solvents are, for example,'methyl alcohol, ethyl alcohol, propyl alcohol or other lower aliphatic alcohol, ethyl acetate, methyl acetate, ethyl formate or other lower aliphatic carboxylic acid ester, and the like. In the event the organic liquid solvent for the dyestuff is not a, swelling agent for the organic acid ester of cellulose, the dyebath will also contain a suitable swelling agent for this material, such as, for example, potassium thiocyanate, acetic or other lower aliphatic acid, acetone, methyl-ethyl-ketone or other ketone,

glycerol butal, ethylene chlorhydrin, glycerol monochlorhydrin, triethyl phosphate, dioxan, glycerol formal or butyl carbitol. The dyebath may also contain water, benzene, toluene, xylene, carbon tetrachloride, dichoroethylene, trichlorethylene and other diluents which are inert to the organic acid ester of cellulose and which serve to limit the swelling action of the dyebath.

In dyebaths for dyeing and partially or completely saponifying staple fibers having a basis of cellulose acetate or other organic acid ester of cellulose, the dyebath will contain, in addition to the dyestufi, a saponifying agent such as, for example, sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate or trisodium phosphate. The dyebath may, in this case, also contain a buffering agent such as, for example, sodium acetate, sodium propionate, or sodium butyrate, to control and make more uniform the saponification of the staple fibers.

The following examples are given to illustrate this invention further.

Example I Tows of cellulose acetate having a total denier of 350,000 and an acetyl value of 54.5%, calculated as acetic acid, are converted into staple fibers and the staple fibers are mixed with a sufficient quantity of an aqueous dyebath maintained at 90 C. and containing 1.0% byweight of sodium hydroxide, 1.7% by weight of sodium acetate, 4% by weight of sodium chloride and 1.0% by weight of Fastusol Grey L. V. G. L. A. (P. R. 379) to produce a mixture having a fiber content of about 1.2% by weight. The mixture so formed is passed through an enclosed passageway having bafiles therein for imparting turbulence to the dyebath and after 15 seconds the staple fibers are separated from the dyebath, washed, drained and finally dried. There are obtained staple fibers having an acetyl value of about 44%, calculated as acetic acid and a grey color which is of excellent fastness.

Example II 4 passageway having baifies therein for imparting turbulence to the dyebath and after 18 seconds the staple fibers are separated from the dyebath, washed, drained and finally dried. There are obtained staple fibers having an orange color of excellent fastness.

. It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of my invention.

Having described my invention, what I desire to secure by Letters Patent is:

1. In a process for dyeing and at least partially saponifying staple fibers having a basis of cellulose acetate, the steps which comprise mixing the staple fibers with a sufficient quantity of a dyebath containing a saponifying agent and a dyestuff having an affinity for the cellulosic material to form a mixture having a fiber content of less than about 2% by weight, and flowing the mixture through an enclosed passageway as the dyeing and at least partial saponification of the staple fibers take place.

2. In a. process for dyeing and at least partially saponifying staple fibers having a basis of cellulose acetate, the steps which comprise mixing the staple fibers with a suificient quantity of a dyebath containing sodium hydroxide, sodium acetate and a dyestuif having an affinity for cellulosic material to form a mixture having a fiber content of less than about 2% by Weight, and passing the mixture through an enclosed passageway as the dyeing and at least partial saponification of the staple fibers take place.

THOMAS H. HILLIARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Technical Association Papers for 1944, 27th Series, pages 309 to 314' (Article by Gray and Akker). 

1. IN A PROCESS FOR DYEING AND AT LEAST PARTIALLY SAPONIFYING STAPLE FIBERS HAVING A BASIS OF CELLULOSE ACETATE, THE STEPS WHICH COMPRISE MIXING THE STAPLE FIBERS WITH A SUFFICIENT QUANTITY OF A DYEBATH CONTAINING A SAPONIFYING AGENT AND A DYESTUFF HAVING AN AFFINITY FOR THE CELLULOSIC MATERIAL TO FORM A MIXTURE HAVING A FIBER CONTENT OF LESS THAN ABOUT 2% BY WEIGHT, AND FLOWING THE MIXTURE THROUGH AN ENCLOSED PASSAGEWAY AS THE DYEING AND AT LEAST PARTIAL SAPONIFICATION OF THE STAPLE FIBERS TAKE PLACE. 